Latching mechanism for switch and lock movements



w. R. GRACEY, JR 2,634,365

LATCHING MECHANISM FOR SWITCH AND LOCK MOVEMENTS April 7, 1953 5Sheets-Sheet l Filed Sept. 30. 1950 INVENTOR.

Will?. R @Pacey JI. BY

HIS ATTRNEY April 7, 1953 w. R. GRACEY, JR

LATCHING MECHANISM FOR SWITCH AND LOCK MOVEMENTS Filed Sept. 30. 1950 3Sheets-Sheet 2 INVENTOR. lfb'lliam. Grace BY HIS ATTORNEY @l Smm. @wmum. Nm.

April 7, 1953 w. R. GRACEY, .JR 2,634,365

` LATCHING MECHANISM FOR SWITCH AND Loox MovEMENTs Filed sept. so, 195o`s sheets-sheet s 17a l/| 5I 2.9 52 57 l J .56 \\V\\\\\\\\\\ Fig?lINVENTOR. filliam A?. Gracey? [Pag By l HIS ATTHNE'Y Patented Apr. 7,1953 UNITED STATES PATENT OFFICE LATCHING MECHANISM FOR SWITCH AND LOCKMOVEMENTS tion of Pennsylvania Application September 30, 1950, SerialNo. 187,770

Claims. l

My invention relates to railway switch operating mechanisms, andparticularly to improvements in the latching mechanism shown anddescribed in Letters Patent of the United States No. 2,184,870 grantedto Herbert L. Bone and Kenneth J. J. McGowan on December 26, 1939. forRailway Switch Operating Mechanisms.

In the aforesaid patent, the latching mechanism comprises a springbiased pivoted point detector lever cooperating with the point detectorrod secured to the switch points of the switch. The point detector levercooperates with a rocker arm of the circuit controller provided for theswitch operating mechanism. Integral with the point detector lever is alatch arm having a latch dog which cooperates with a spring biasedpivoted latching member. The parts are so proportioned and adjusted thatwhen the switch is trailed, the movement of the switch point away fromthe stock rail wil1 cause the point detector rod to move, to pivot thepoint detector lever. The rotation of the point detector lever rotatesthe rocker arm of the circuit controller to close signal controlcontacts which when closed will set the signals governing traffic overthe switch to stop The rotation of the point detector lever also rotatesthe latch arm so that the latch dog enters the notch of the latchingmember to hold the point detector lever in its rotated position.Consequently, the rocker arm of the circuit controller is held in itsrotated position to hold the signal control contacts closed.

In order to clear the signal for traffic moving over the trailed switch,the latching member may be reset by hand, or the switch operatingmechanism may be operated to move the switch to its opposite position,in which event a cam dog' carried by the lock bar will engage a cam armon the latching member to release the latching member.

Under conditions of operation where the switch and lock movement issubject to excessive vibration due to the pounding on the rails of apassing train over the switch, a longitudinal load is sometimes suddenlyapplied along the axis of the point detector bar which is transmitted tothe lever latch arm. The lever latch arm is thus displaced downwardly topermit the latch dog to enter the notch of the latching member and afalse latchout occurs. While the latching device may be reset byoperating the movement to reverse the switch points, the false latchoutscause some delay and inconvenience.

It is therefore an object of my invention to provide a novelself-restoring latching device for a switch and lock movement in whichfalse latchouts due to excessive vibration and shock are substantiallyreduced.

In carrying out my invention I provide the latching member of thelatching device with a cam surface which cooperates with the latchingdog carried by the lever latch arm. When the lever latch arm is suddenlydisplaced in the manner hereinbefore indicated, the latching dog willabut the camming surface to throw the latching member out of the way tokeep the latching dog from engaging the latching member notch. As thedisplacement and return of the lever latch arm is very rapid when ashock load occurs, suiicient time is provided in throwing the latchingmember out of the was7 to permit the lever latch arm to return to itsnormal position before the latching member returns to its normalposition. Thus with the return of the lever latch arm to its normalposition before the latching member, false latchouts will be prevented.

I shall describe two forms of latching mechanisms embodying myinvention, and shall then point out the novel features thereof inclaims.

In the accompanying drawings, Fig. 1 is a view showing a railway switchoperated by a switch operating mechanism in which my novel latchingmechanism is incorporated. Fig. 2 is a vertical longitudinal sectionalview of the switch operating mechanism shown in Fig. 1. Fig. 3 is asectional view on an enlarged scale taken substantially along the lineIII-III of Fig. 2. Fig. 4 is a top plan view of the circuit controllerend of the switch operating mechanism with the cover removed. Fig. 5 isan enlarged elevational view of the latching mechanism embodying myinvention showing the latching members in their unlatched positions,while Fig. 6 is an enlarged elevational view of a second embodiment ofmy latching mechanism.

Similar reference characters refer to similar parts in each of theseveral views.

Referring to Fig. l, the reference character A designates a railwayswitch comprising two fixed rails I and la and two movable rails orswitch points 2 and 2a. The fixed rails are laid on tie plates 3 and aresecured to crossties 4 in the usual manner. IThe switch points 2 and 2aare fastened together by means of a front rod 5 and a head rod 6, andmay be moved into a normal or reverse position by means of a throw rod'l which is connected to the head rod by way of a switch basket 8. Whenthe switch A occupies its normal position as illustrated in Fig. 1. theswitch point 2 engages the fixed rail l 3 while the switch point 2a isspaced from the xed rail Ia. When the switch A is reversed, the switchpoint 2a engages the fixed rail ia while the switch point 2 is spacedfrom the fixed rail I.

Secured to the elongated crossties d adjacent the outer side of rail Iis a switch and lock movement B more fully described in the aforesaidLetters Patent of the United States No. 2,184,870. In Figs. 2, 3, and 4of the drawings, sufficient details of the switch and lock movement areillustrated which, when considered with the description hereinaftergiven, will be adequate for an understanding of the operation of theparticular movement.

A suitable casing 9 encloses the operating parts of the movement B, areadily removable cover I9 giving access to the parts. Located withinthe casing 9 is a motion plate II adaptedV to slide longitudinally in adirection parallel to the track by means of guide rollers I2 secured tothe underside of the motion plate and cooperating with suitableguideways I3 provided on the bottom wall of the casing 9. The uppersurface of the motion plate is formed with rack teeth I4 which mesh witha segment gear I5 mounted on a square shaft I6. The ends of the shaft I6are mounted in bearing sleeves Il and I'Ia journaled in bosses I8 formedin the sidewalls of the casing 9. Secured to an outer end of the shaftI6 as by a bolt I9 is a hand-throw lever 26 which serves as a means forreciprocating the motion plate I I from one extreme position to theother.

Means are now provided for moving the switch points 2 and 2a into theirnormal and reverse positions and locking the points in their extremeposition upon Vmovement of the motion plate II from its one extremeposition to its other extreme position. To this end a roller 2I issecured to the underside of the motion plate at a point intermediate therollers I2. The roller 2| cooperates with cam faces (not illustrated)formed on an escapement crank 22. The escapement crank 22 is formedintegrally with the upper end of a vertical switch actuating shaft 23suitably7 journaled in bearings 24 and 25 formed respectively in thebottom of casing 9 and a depending stirrup 26 provided on the undersideof the casing. Secured to the shaft 23 is a switch operating arm 21, theend of which is pivotally connected (not shown) to the free end of thethrow rod 1.

operatively connected to the motion plate II by mea-ns of a stud 28 is alock bar 29 extending longitudinally of the casing directly above themotion plate. The lock bar 29 is slidably mounted at one end in a guideplate 36 secured to the end of the casing and at the other end in aguideway 3l formed in a frame 32 bolted to the casing adjacent theleft-hand end thereof. The stud 28 is secured to the lock bar andextends into a transversely extending slot IIa. formed in the upper sideof the motion plate. The left-hand end of the lock bar 29 (Fig. 2)cooperates with a notch 34 provided in a lock rod 35 which is secured tothe front rod 5. The parts are so proportioned that when and only whenthe switch occupies its full normal position, the notch 34 will bealigned with the lock bar, and when the motion plate II is in itsextreme left-hand position, the lock bar will enter the notch 34 asshown in Fig. 2 to lock the switch in its normal position.

The operation of the portion of the apparatus thus far described will beapparent to those versed in the art. When the hand-throw lever isrotated to the normal position illustrated in the drawings, the motionplate II is moved to its extremelefthand position as illustrated in Fig.2. The switch points are held in the position illustrated in Fig. l byengagement of the roller 2I with the cam surface of the escapement crank22, the lock bar 29 entering the notch 34 of the lock rod 35 to lock theswitch points in their normal position. To reverse the switch, thehand-throw lever 26 is rotated in a counterclockwise directionapproximately from its one extreme position to the other. Segment gearE5 will be rotated by the hand-throw lever to' move the motion plate I Ito its extreme right-hand position. The initial movement of the motionplate will withdraw the lock bar 29 from the notch 34 in the lock rod 35to unlock the switch, the continued motion of the motion plate causingthe escapement crank to be rotated by engagement of the roller 2I andthe camsurface carried. by said crank, the crank in turn rotating theswitch actuating shaft 23 to rotate the switch operating arm 27 to movethe throw rod I causing the switch points 2 and 2a to move to theirreverse position. To restore the switch to its normal position, theoperation of the parts is exactly the reverse of that described.

` The switch and lock movement B also includes a circuit controller forcontrolling the signals governing tramo movement over the switch A. Thecircuit controller comprises a rocker arm 36 pivotally supportedintermediate its ends on a pin 3la secured within a pair of spacedupstanding lugs 31 provided on the frame 32. The rocker arm 36 isdisposed directly above the lock bar 29, and is provided with a cam face36a (Fig. 6) which cooperates with a cam face 38a. provided on a cam dog38 (Fig. 2) secured to the upper surface of the lock bar 29 in such amanner that when the lock bar is moved to the position in which it iswithdrawn from notch 34 in the lock rod 35, the cam face 38a will engagethe cam face 36a, shortly before the lock bar has cleared the notch.rJhe rocker arm 33 will thus be rotated in a counterclockwise direction(Fig. 2) from its normal position illustrated to its extreme reverseposition. The rocker arm 33 is further provided with a cam face 36hwhich joins the right-hand end of the cam face 36a. The cam face 36hcooperates with the top of the cam dog 36 to maintain the rocker arm 36in its extreme reverse position whenever the switch is unlocked.

A contact operating member 39 (see Fig. 3) is pivotally attached to theleft-hand end of the rocker arm 36, and is guided to move vertically bymeans of upwardly extending studs 46 which are provided on the frame 32,and which pass freely through clearance holes formed in the contactoperating member. Surrounding the studs between the frame and thecontact operating member are compressed coil springs 4I, whereby theoperating member is biased to an upper position in which it engagesadjustable stop nuts 42 screwed onto the upper ends of the studs, itbeing noted that since the Contact operating member is pivotallyattached to the rocker arm 36, the springs 4I also serve to bias therocker arm to its normal position in which it is shown in Fig. 2. Twosuperimposed insulating blocks 43 and 44 are secured to the uper side ofthe operating member, and extending between these blocks are the freeends of a plurality of iiexible contact fingers 46, here shown as fourin number. Each contact nger 45 cooperates with a xed contact member 46to form a contact I5- 46. Each contact finger 45 and the associatedcontact member 46 are Vclamped to the opposite 'sides of an insulatingblock 41 by means of terminal posts 48 and the insulating block 41, inturn, is supported on lugs 49 projecting upwardly from the frame 32. Theparts are so proportioned that when the rocker arm 36 occupies itsnormal extreme position in which it is shown in the drawing, eachcontact 45--46 will be open, but when the rocker arm is rotated to itsother extreme position, each contact 45-46 will then be closed. It willbe apparent, therefore, that the contacts 45-46 will become closedwhenever the lock bar 2'9 is withdrawn from the notch 34 in the lock rod35 to unlock the switch.

The circuit controller also comprises a point detector lever 50 (Figs.2, 3, and 4) which is pivvotally supported on a pin 5l mounted in theframe 32. An anti-rattler spring 52 is interposed between the frame anda laterally projecting latch arm 53 on the point detector lever tendingto bias the point detector lever in a counterclockwise direction to theposition in which a roller 54 mounted in a depending lug 55 formed onthe point detector lever enters a notch 56 in a point detector rod 51.The point detector rod 51 is slidably mounted in the casing 9, and asshown in Fig. 1 is attached, by means of a link 58 and a bolt 59 to themovable rail 2 of the switch A in the usual and well-known manner. Thepoint detector lever 50 is also provided with a laterally projecting arm60 having a rounded end 6l which overlies and cooperates with theconical head 62 of a finger 63 which is adjustably mounted in anupstanding lug 64 provided on the rocker arm 36. The springs 4I biasingthe rocker arm 36 in a clockwise direction also provide the majorbiasing force for maintaining the roller 54 in the point detector rodnotch 56 through the cooperation of the conical head 62 of the nger 63mounted on the rocker arm and the rounded end 6I of the point detectorlever arm 60.

The notch 56 in the point detector rod 51 is so disposed and the partsare so proportioned that the roller 54 will enter the notch 56 when andonly when the movable rails 2 and 2a of the switch A occupy their normalextreme positions and the movable rail 2 is in proper engagement withthe xed rail I. The parts are further so proportioned that when theroller 54 is within the notch 56 and the rocker arm 36 occupies itsnormal position, therounded and 6| of the point detector lever willengage the upper side of the conical head 62 of the linger 63, but whenthe roller 54 is forced out of the notch 56, the resultant clockwiserotation of the point detector lever Will cause the rounded end 6i ofthe point detector lever to cooperate with the head 62 of the finger 63to rotate the rocker arm 36 to its reverse extreme position, thuscausing the contacts 45-46 to become closed. It follows, therefore, thatany displacement of the switch point 2 away from the rail I in excess ofthe normal safe distance when the parts are in the positions shown inthe drawings will operate the contacts.

vAs pointed out in the aforesaid patent, the contacts of a circuitcontroller are utilized to control sgnals governing traffic over theassociated switch. Their primary purpose is to cause the signals toindicate stop unless the switch points occupy their proper positionsrelative to the xed rails and are properly locked in these positions. Ifa train improperly trails the switch while it is locked in its normalposition, the switch points will be displaced an amount which willoperate the point detector contacts of the circuit controller bymovement of the point detector rod. In order to detect-the trailedvcondition of the switch, a

6. latching'mechanism was provided in the afore-v said patent whichretained the circuit controller contacts in their closed positions untilthey were subsequently released by a maintainer. The signals governingtraffic over the switch thus containued to display a restrictiveindication until the maintainer released the contacts of the circuitcontroller and permitted them to return to their normal positions. Whilethe latching' mechanism described in the aforesaid patent workedsatisfactorily in retaining the circuit controller contacts in theirclosed positions when the switch was trailed, false latchouts occuredoccasionally in installations subjected to excessive vibrations.latching mechanism which will eliminate these false latchouts.

The novel latching mechanism embodying my invention comprises thepreviously referred to latch arm 53, the free end of which is providedwith a latch dog 65 having a rounded end or camming surface 65acooperating with a latch catch 66. The latch catch is provided with ascrew threaded upper portion S1 adjustably screwed through a tapped holein an extending arm 68 of a U-shaped latching member 69 pivotallysupported at its ends on a rod 10 mounted in the upstanding lugs 1! onthe frame 32. The latch catch 66 is locked in its desired position onthe latching member arm 68 by means of a lock washer 12 and a jam nut 13provided on the threaded portion 61 above said arm. The latch catch(Fig. 5) is formed with parallel sides 14 terminating at the lower edgesin outwardly extending sides or cam faces 15. The cam faces 15 in turnterminate in two sides or cam faces 16 with a slope approximately equalbut opposite in sign to the slope of the cam faces 15. The cam faces 16terminate in two sides 11, hereinafter referred to as shoulders 11. Theshoulders 11 are angularly disposed to a slight extent with the parallelsides 18 on the lower end of the latch catch 66.

The U-shaped latching member 69 pivoted on the rod 16 is provided with acam arm 86 extending towar-d the right (Figs. 2, 4 and 6), the lower endof the arm being provided with a cam face 86a. which cooperates undercertain conditions hereinafter described with the cam dog 38 carried bythe lock bar 29. The latching member 69 is biased to rotate in aclockwise direction (Fig. 2) by the cam arm B0 and by a spring 8l whichis connected at one end to a projecting lug 82 on the frame 32 and atthe other end to a spring arm 83 provided on the latching member.

The parts of the latching mechanism described are so proportioned andthe latch catch 66 is so adjusted that when the roller 54 on the pointdetector lever 5i] is within the notch 56 of the point detector rod 51and the lock bar 29 is in its locking position in which the left-handend of the bar is within the notch 34 of the lock rod 35 as shown in thedrawings, the point 0i. juneture of the sides 14 and 15 of the latchcatch 66 will engage the rounded end 65a of the latch dog 65 on thepoint detector lever 50. The latching member 69 will thus be preventedfrom rotating in a clockwise direction (Fig. 2) about the rod 16 by thespring 8| and the cam arm 80.

Assuming the switch A to be in its normal position as illustrated inFig. l and the switch is moved to its reversed position by means of thehand-throw lever 20 in the manner described, the movementofvthe lock bar29 in withdraw-j I have accordingly provided a novel accesos ing Afromthe notch 34 in the lock rod 35 will cause the cam face 38a of the camdog 38 vto engage the cam face of the cam arm 36 to rotate the latchingmember v69 in a counterclockwise direction against the Abias of thespring 61. The latch catch 6.6 will accordingly be rotated in the samedirection to a position out of vengagement with the latch dog `65. Thecam face 36a will also engage the cam face 36a on the rocker arm 36 androtate the rocker arm from the normal extreme position illustrated toits reverse extreme position to Aclose the contacts i5-,46. The'motionof the'rocker arm 36 also lowers the finger 63'to such a position thatwhen the switch points subsequently start to move and force the roller54 out of the notch 56 in thepoint detector rod 51, the point detectorlever 55 will be free Yto rotate without causing the rounded end 6l ofthe arm 66 of the point detector lever to engage the conicalhead 62 ofthe nger. The continued motion of the lockbar 29 after lthe roller 54 isforced out of the notch 56 in the point detector rod 51 will cause thecam dog 38 to move past the cam face 80a of the cam arm to permit thelatching member 69 to rotate in a clockwise direction (Fig. 2) to theposition in which'the cam arm 86 engages the lugs 31 which support thepin 37a., but the dog 38 will continue to engage the Arockerarm cam face36h during the remainder'of the movement of the lock bar. The rocker armwill thus `be retained in its reverse f extreme position.

When the hand-throw lever 26 is operated to restore the switch to thenormal position illustrated in Fig. 1, the operation of the circuitcontroller will be substantially the reverse of that just described. Thelatching member 68 will be rotated to the position in which the latchcatch 66 is clear of the latch dog 65 due to the engagement of the camsurface 36h provided on the cam dog 38 with the cam surface 86a on thecam arm 80. The latch catch willbe retained in this position until afterthe notch 56 of the point detector rod moves into alignment with theroller 54 by the engagement of the top of the cam dog 38 `with the camsurface 80a. Inasmuch as the operation of the circuit controller duringmovement of the switch points to their normal positions in substantiallythe reverse of that which has been described in connection with themovement of the switch points to their reverse positions, it is believedthat the operation of thercircuit controller during this return movementwill be understood from an inspection of the, drawings and from theforegoing description.

Assuming now that the switch A is in the normal position'illustrated inFig. l and that the parts are in the positions shown in the drawingsV'an'd'that a train trails the switch. vUnder these conditions, thetrailing train will move the switch point 2 away from stock rail I 'tomove the point detector rod 5? to the left as Vseen in Fig. 3. Theroller 54 will be forced out ofthe notch 56 Vcausing the point-detectorlever to rotate in azclockwise direction (Figs. 2 and "6). The clockwiserotation of the point detector lever will act through the arm 69 andnger'63 to rotate the rocker arm 36 in a counterclockwise direction aboutits pivot 31a to its extreme extreme reverse position to close thecontacts 45-46.

The rotation of therpoint detector lever 56 will also move the latch'arm53 downwardly to'xnove the latch dog 65 downwardly. VThe Ndownwardmovement of the latch dogwill cam the'. vlatch catch 66 in acounterclockwise direction while in engagement with the sides "I5 of thecatch. The continued downward movement of the latch dog past the sidesI6 of the latch `catch will permit clockwise rotation of ythe latchcatch due to the influence of the spring 3l.; the top surface 65h oflatch dog engaging the shoulder 7T when the latch dog has been moved toits extreme downward position. The point detector lever 50 will be heldin a position in which the roller 54 is out ofthe notch Y56 ofthe'lpoint detector rod and the-rocker arm 36 will be held in itsextreme reverse position by rthe arm 6,5 and viinger 63. The contacts45-46 will 4thus be held closed until vthe latching mechanism isrestored to its unlatched-position.

To release the contact operating member vand permit the contacts 45-'46to open after "they havebeen closed in the `manner described, Ythe coverI0 of the casing maybe removed landthe cam arm raised, the spring 52returning the point detector lever 50 and consequently the latch dog 65to their normal positions, providing of course that the roller 54 of thepoint detector lever enters the point detectorrod notch 56. The contacts45-46 may also be openedby operating the'switch movement to its reverseposition, the cam dog 38 raising the cam arm 80 to release thelatch'catch. Should the switch points be damaged and the switch movementsubsequently operated to its normal position, the roller '54 on thepoint detector lever will not enter the point detector rod notch 56 dueto the damaged switch points.

From the foregoing description of the latching mechanism and itsyoperation it is evident that the novel mechanism provided will hold theYpoint detector lever 56 in its extreme reverse position when the switchA is trailed. My novel latching mechanism is further characterized bythe kfact that alse latchouts due to excessive yvibration and shock areeliminated. As is well known in the railroad art, the pounding of thewheels over the rails set up vibration which can and does affectequipment connectedwith or installed adjacent to the rails. In the casevof switches-the poundingv on the rails is'transmitted through the pointdetector rod to the'point detector'lever. The suddenly applied shockalong the Yaxis of the pointl detector rod transmitted through theroller of the point detector lever tended torotate the point detectorlever and itsfassociated latch-arm and latch dog.

In the latching mechanism herein-provided-the problem presented byfalse'latchouts is 4eliminatedV by providingrstly, a'spring (4I) forbiasingthe point detector lever whose natural frequency of operation is'different than the shock frequency set up'by the'rails, and secondly,Vby providing the latch catch with camming surfaces which are engaged bythe latch dogof the latch arm, lthe camming surfaces beingsuch that thelatch catch is kicked out of the way for a sufficient kperiod of `timebythe movement of `the latch dog to allow the latch dog to return'to'itsinitial position.

Referring'toFig. 5 in which the latching mechanism isshown in its normalor unlatched position, it will be noted that the rounded tip end 65a ofthe'latch dog .65Aengages the surfaces 14 and 16. The downward movementofitherlatch dog'will throw the latch .catch 66 inravcounter, clockwisedirectionaboutits ypivot 'l0 away from the f latch dog. Incthe ncase ioffa trailed '-swtch.

the roller '54 engages the point detector rod 51 so that the latch dogis held in its latching position. The return of the latch catch to itslatching position will permit the top surface 65h of the latch ldog tocatch under the shoulder 11 to latch out the mechanism. Now, should thelatch dog 65 be displaced in a downward direction, as in the case ofshock loads applied to the point detector rod, the camming action of thelatch dog end 65a, and surface 15 will throw the latch catch to theright in a counterclockwise direction about its pivot. The latch dogwill return to its unlatched position under the influence of springs 4land to some extent spring 52, the roller 54 reentering the pointdetector rod notch 56. The angular displacement of the latch catch willpermit the latch dog 65 to return to its unlatched position before thelatch catch 66 returns to its normal position, thereby preventing themechanism from latching up. It will be appreciated from the drawing thatthe latch dog 65 need not return to its extreme normal positionillustrated before the return of the latch catch. Should the latch catchrecover from its throw so that the latch catch surface 15 engages thelatch dog end 65a, the latch dog will be returned to its extreme normalposition by the spring 4I which is stronger than the return spring 8|for the latch catch.

In Fig. 6 I have illustrated a second embodiment of my invention inwhich a latch catch 84 is provided having a screw threaded upper portion85 adjustably screwed through the tapped hole in the extending arm 68 ofthe latching member 69. The latch catch 8d is formed with two outwardlyand downwardly sloping sides 8B terminating in a shoulder 81.

The operation of the latching mechanism illustrated in Fig. 6 is similarto that shown in Fig. 5. Downward movement of the latch dog 65 willthrow the latch catch in a counterclockwise direction in the mannerheretofore described. In the case of a trailed switch, the top surface65h of the latch dog will engage the shoulder 81 of the latch catch tolatch up the mechanism. In the case where shock loads are transmittedthrough the point detector rod, the downward movement of the latch dogwill throw the latch catch to the right out of the way a suicient lengthof time to permit the latch dog to return from its latching position,thereby preventing false latchouts.

It will be appreciated from the foregoing that I have provided a novellatching arrangement for switch and lock movements by which the circuitcontroller contacts of the movement are held in their restrictive signalposition when the switch is trailed and which prevents false latchoutsof the circuit controller contacts in installations of the movementwhere excessive vibration and pounding prevail.

Although I have herein shown and described only two forms of a latchingmechanism for a switch and lock movement embodying by invention, it isunderstood that various changes and modifications may be made thereinwithin the scope of the appended claims without departing from thespirit and scope of my invention.

Having thus described ymy invention, what I claim is:

l. A. latching mechanism comprising a pivoted latch dog biased in a -rstdirection to an unlatched position and adapted to be moved in anopposite direction and held in a latching position, a pivoted latchcatch having at least one cam surface and a shoulder, and biased in anopposite direction toward a latching position, said cam surfaceengagingsaidlatch dog when said latch dog is in its unlatched position, saidlatch dog moving in said opposite direction toward its latching positioncamming said latch catch in said rst direction away from said latch dog,said latch dog engaging the shoulder of said latch catch only when saidlatch dog is held in its latching position.

2. A latching mechanism comprising a pivoted latch dog biased in a rstdirection to an unlatched position and adapted to be moved in anopposite direction and held in a latching position, a pivoted latchcatch having rst and second cam surfaces with slopes of opposite signsand a shoulder, and biased in an opposite direction toward a latchedposition so that said first cam surface engages said latch dog whenlsaid latch dog is in its unlatched position; said latch dog moving insaid opposite direction toward its latching position sliding over saidrst cam surface of said latch catch and camming said latch catch in saidfirst direction away from said latch dog, said latch dog engaging saidshoulder of said latch catch only when said latch dog is held in itslatching position, said second cam surface of said latch catchpermitting the latch dog moving in said first direction from itslatching position to slide over said second cam surface and then oversaid first cam surface to return to its unlatched position.

3. In a switch operating mechanism for a railway switch having means formoving the movable rails of said switch between an extreme normalposition and an extreme reverse position and locking said movable railsin an extreme position, a point detector rod secured to said movablerails and provided with a notch, a pivoted point detector lever providedwith a roller biased to engage said point detector rod and to enter thepoint detector rod notch when and only when said switch is locked in anextreme position, and a contact operating member held in an operativeposition when said roller is forced out of the point detector rod notch,the combination of a latching member movable with said point detectorlever, a pivoted latch member biased to a latching position, saidlatching member throwing said latch member away from the latching memberwhen said roller is forced out of the point detector rod notch and heldupon the return of said latch member to its latching position by saidlatch member when said roller engages the'point detector rod to holdsaid'contact operating member in its operative position, suddenlyapplied longitudinal loads on said point detector rod causing saidlatching member to throw said latch member away from said latchingmember a period of time sufficient to permit the latching member toreturn to its initial position before said latch member returns to itslatching position.

i. In a switch operating mechanism for a railway switch having means formoving the movable rails of said switch between an extreme normalposition and an extreme reverse position and locking said movable railsin an extreme position, a point detector rod secured to said movablerails and provided with a notch, a pivoted point detector lever providedwith a roller biased to engage said point detector rod and to enter thepoint detector rod notch when and only when said switch is locked in anextreme position, and

a contact operating member held in an operative position when saidroller is forced out of the point detector rod notch, the combination ofa latch dog movable withY said point detector lever; a

pivoted latch catch havingat least one camsurJ- face and a shoulder, andbiased to a latching Aposition so that said cam surface engages saidlatch dog; said. latch dog camming said latch catch away from said latchdog when said roller is forced out of the point detector rod notch andengaging said shoulder upon the return of said latch catch to itslatching positionA when said roller engages said point detector rod tohold said latch dogr and latch catch in a latched condition and to holdsaid contact operating member in its operative position, suddenlyappliedlongitudinal loads on said point detector rod causing said latchdog to cam said latch catch awayY from said latch dog a period of timesuiiicient to permit the latch dog to return to its initial positionbefore said latch catch returns to its latching position.

5. In a switch operating mechanismrfor. a railway switch having meansfor moving the movable rails orV said lswitch between an extreme normalposition andan extreme reverse position and locking said movable railsin an extreme position, a point detector rod secured to said movablerails and provided with a notch. a pivoted point detector lever providedwith a roller biased to engage said point detector rod and to enter thepoint detector rod notch when and only when said switch is locked in anextreme position, and a contact operating member held in an operativeposition when said roller is forced out of the point detector rod notch,the combination of a latch dog'movablewith. said point detectorv lever;a pivoted latch catch having first and second camV surfaces. with slopesof opposite signs and a shoulder,.and. biased to a latching position sothat said first cam surface engages said latch dog; said latch dogcamming said latch catch away from said latch dog when said roller isforced out of said point detector rod notch and engaging' said shoulderuponthe return of said latch catchtov its latching position when saidroller engages said point detector rod to hold said latch dog and latchcatch in a latched condition and to hold said contact operating memberin its operative position, suddenly applied longitudinal loads on thepoint detector rod causing said latch dog to'cam said latch catch awayfrom said latch dog a period ofl time suicient to permit said latch dogto return to its initial position before 'said latch catch returns toits latching position, said secondV cam surface being such to permitsaid latch dog to slide thereover in its return to its initial positionshould the second cam surface engage the latch dog.

WILLIAM R. GRACEY, J R.

REFERENCES CITED UNITED STATES. PATENTS Name Date Bone et al. Dec. 26,1939 Number

